This is a tough one to handicap.
I'm with the others that the ancillary charcters are going to take a big hit, and soon. Jorah, Tormund, Beric, Edd, Theon, Grey Worm, Pod. All goners in the battle to come. I think the Jamie - Brienne prediction is a good one, one or both will die. Tougher call with the Hound, Gendry, Lyanna Mormont, Sam.
Core Cast: somebody has to die from: Jon, Dany, Arya, Sansa, Tyrion, Bran, Jamie. Just Jamie would be weak. The most uncomplicated situation is that Dany and all three dragons die, along with the Night King. That leaves Jon as the sole heir to go to war against Cersei. Sansa is then free to back him as 50/50 Stark - Targaryen.
Problematic plot devices:
- XX chromosome bowl: Jon dies, Sansa and Dany go to war vs. Cersei. Maybe with little Lyanna Mormont and Lara. Lame.
- Who cares about the throne?: Jon and Dany die. Sansa would leave Cersei alone in Kings Landing. Tyrion would need to make the push. I don't see Gendry having it in him.